3. FOOD ChEMISTRy & bIOTEChNOLOGy 3.1. Lectures
3. FOOD ChEMISTRy & bIOTEChNOLOGy 3.1. Lectures
3. FOOD ChEMISTRy & bIOTEChNOLOGy 3.1. Lectures
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Chem. Listy, 102, s265–s1311 (2008) Food Chemistry & Biotechnology<br />
The obtained dependence can be effectively used as calibration<br />
curve enabling the estimation of previously absorbed<br />
dose. 5,9–11<br />
Relative radical content, a.u.<br />
1.00<br />
0.75<br />
0.50<br />
0.25<br />
0.00<br />
2 34 61 98 128 190<br />
Time after γ-irradiation, day<br />
Semiquinones<br />
Carbohydrates I<br />
Carbohydrates II<br />
Carbohydrates III<br />
Carbohydrates IV<br />
Fig. 2. The dependence of relative radicals’ content on time<br />
after the γ-irradiation obtained from the simulation analysis of<br />
experimental EPR spectra of caraway sample treated at dose of<br />
30 kGy<br />
Relative ABTS •+ concentration, a. u.<br />
1.00<br />
0.75<br />
0.50<br />
0.25<br />
0.00<br />
4 HN 3 OS<br />
CH 2 CH 3<br />
CH 2 CH 3<br />
S<br />
N N<br />
S<br />
3 6 9 12 15 18<br />
Time after ABTS •+ addition, min<br />
SO 3 NH 4<br />
Reference<br />
0 kGy<br />
5 kGy<br />
10 kGy<br />
20 kGy<br />
30 kGy<br />
Fig. <strong>3.</strong> The dependence of relative AbTS •+ concentration on<br />
time after its mixing with caraway ethanolic extracts prepared<br />
from samples exposed to different doses of γ-radiation. Inset<br />
represents the structural formula of AbTS. Extracts were prepared<br />
2 days after the irradiation. Pure ethanol was used as reference<br />
As a result of irreversible decay of radical structures<br />
induced by γ-radiation, the integral EPR spectra intensity<br />
of irradiated samples decreased gradually as is clearly<br />
demonstrated on Fig. 1. and Fig. 2. for caraway samples. On<br />
the contrary, the signal intensity of both reference samples<br />
remains practically unchanged.<br />
s562<br />
Detail evaluation of experimental spectra revealed the<br />
lowest stability of cellulosic radicals in laurel leaves (half life<br />
∼ 10 weeks) followed by carbohydrate radicals, which stability<br />
ranged from 20 up to 60 weeks. These results are in good<br />
agreement with our previously published papers. 5,9–11<br />
Ethanolic extracts of both reference spices revealed significant<br />
ability to terminate • DPPH as well as ABTS •+ radicals.<br />
As demonstrated on Fig. <strong>3.</strong>, it is only slightly influenced<br />
by the absorption of γ-radiation. Results obtained moreover<br />
showed, that radical-scavenging ability of laurel leaves’<br />
extracts is significantly higher than that of caraway; probably<br />
due to the differences in types and concentrations of polyphenolic<br />
compounds.<br />
UV-VIS experiments proved, that radiation treatment<br />
resulted in significantly increased • DPPH radical-scavenging<br />
activity of bay leaves methanolic extracts. In addition, the<br />
TBARS value of caraway extracts, representing a measure of<br />
oxidative products concentration, was slightly increased. As<br />
a result of post-irradiation storage, a minor increase of ferric<br />
reducing power, • DPPH radical-scavenging ability as well as<br />
content of polyphenolic compounds of bay leaves extracts<br />
was noticed, whereas the TBARS values of both, caraway<br />
and bay leaves extracts, was somewhat reduced.<br />
Discriminant analysis of all variables obtained from UV-<br />
VIS experiments was used to differentiate the studied spices<br />
according to the absorbed dose. As depicted on Fig. 4., the<br />
effective discrimination was achieved only when non-irradiated<br />
samples and samples treated by dose of 30 kGy were<br />
compared. Using this approach, 93% correctness of caraway<br />
classification was found, influenced mostly by TBARS values<br />
and TPC content. In the case of bay leaves, 73% correct differentiation<br />
of non-irradiated sample from sample γ-irradiated<br />
at 30 kGy was found.<br />
Fig. 4. Canonical discriminant analysis of non-irradiated<br />
caraway samples (C0) and of samples γ-irradiated at 30 kGy<br />
(C30). Characteristics obtained from uV-VIS experiments<br />
( • DPPh, TbARS, FRP, TPC) immediately after the irradiation<br />
and during the storage of samples at ambient conditions were<br />
used as variables